Introduction

Magnetic molecules are a new class of fascinating
materials. These molecules contain a finite number of
interacting spin centers (e.g. paramagnetic ions) and thus
provide ideal opportunities to study basic concepts of
magnetism. Some of them possess magnetic ground states and
give rise to hysteresis effects and metastable magnetic
phases. They may show quantum tunneling of the magnetization
which raises the question of coherent dynamics in such
systems. Other types of molecules exhibit pronounced
frustration effects, whereas so-called spin crossover
substances can switch their magnetic ground state and related
properties such as color under irradiation of laser light,
pressure or heat. Scientists from various fields - chemistry,
physics; theory and experiment - have joined the research on
molecular magnetism in order to explore the unprecedented
properties of these new compounds.